Anatomically customized and mobilizing external support, method for manufacture

ABSTRACT

The present invention relates to an anatomically personalized and mobilizing external support, a method for manufacturing is, as well as the use of a component of an invasively attached external support in determining the path of the joint being supported. In the method according to the invention, the kinetic dynamics of the joint are measured with the aid of a component of an external support invasively attached to two bone groups, on the basis of which an external support is arranged between the bone groups.

The present invention relates to tissue-damage rehabilitation devicesand methods. In particular the invention relates to the creation ofexternal support for damaged tissue, in order to support the tissueduring rehabilitation. More specifically, the invention relates to themethod, device, and use according to the preamble portions of Claims 1,15, and 18.

As is known, the care of serious damage to a synovial joint resultingfrom accidents is challenging. For example, falling accidents oftenresult in serious damage to the ankle, which is caused by the ankle boneimpacting the cartilage surface of the tibia, which in the worst casecan even lead to the crushing of the lower end of the tibia. Recoveryfrom injuries like those described usually takes several months. Intypical care following a falling accident, the damaged ankle is repairedoperatively and fixed, i.e. supported rigidly, using, for example,so-called pilon rings and similar care accessories. However, in order torecover to full functionality, the cartilage requires nutrition, thetransportation of which—unlike that in other tissues—is based on thetissue being loaded in cycles, so that fluid dynamics appear inside thecartilage. The recovery of cartilage is described in detail in thepublication, ‘Influence of cyclic loading on the nutrition of articularcartilage’ (O'Hara B., Urban J., & Maroudas A., Ann Rheum. Dis. 1990July; 49(7): 536-539). If mobilization that transports nutrients is notarranged, the cartilage surface repaired by the operation may bedestroyed, which will be followed in a couple of years by a statecorresponding to osteoarthritis, i.e. invalidity. Precisely becauseosteoarthritis patients are mostly young people or those of working age,such as building workers, invalidizing osteoarthritis leads to not onlypersonal misfortune, but also a significant economic cost.

In the publication ‘Articulated external fixation of the ankle:minimizing motion resistance by accurate axis alignment’ (Bottas M.,March. L., & Brown T., Journal of Miomecanics, Vol. 32, No. 1, January1999, pp. 63-70), it is stated that factors promoting recovery from, forexample, the ankle-fracture injuries referred to above are protectionfrom loads, early post-operative movement, a reduction in splinterfractures, and minimal disturbance of the injured area. For this reason,post-operative supports for damaged joints have been developed, so thatin aftercare it will be possible to take into account mobilization ofthe joint as a precondition for recovery. However, it should be notedthat, besides the mobilization of a damaged joint, its correct timing isof considerable significance in the success of rehabilitation. Forexample, the mobilization of an ankle must be started already two daysafter an operation. Correspondingly, a movement of the wrong kind canhave disadvantageous consequences. It is therefore of decisiveimportance to find to find the joint's anatomically correct path, inorder to minimize the resistance to motion and avoid sudden damagecaused by the wrong kind of movement. Thus, significant expectations aredirected to post-operative supports, in relation to both being able tobe rapidly installed and to creating the correct type of path.

Many external supports are known. However, the majority of supportsintended for the aftercare of synovial joint injuries are either rigid,i.e. the supports do not permit therapeutic movement, or supportspermitting movement, the motion permitted by which is typically a roughapproximation of the real movement of the joint. In a hinge joint, suchthe ankle, movement takes place around only a single axis of rotation,with a limited extent of movement. This is the simplest model of amoving joint, due to which it is used as an illustrative example in thisconnection. In other types of synovial joint, rotation and sliding inthe direction of several axes or planes of movement can take placesimultaneously. These can be controlled equally by means of thetechnology disclosed here. Rigid supports are, among others, Ilizahrovrings, which are external supports attached on both sides of the damagedjoint. Ilizahrov rings are a way of implementing joint support thatpenetrates the tissue, i.e. it is invasive. In the method, the rings areattached to the patient's bone by using tensioning cables and bonescrews. Ilizahrov rings and their use are described in greater detail inthe publications ‘Pilon fractures. Treatment protocol based on severityof soft tissue injury’ (Watson J. T., Moed B. R., Karges D. E., CramerK. E.. Clin. Orthop. 2000; 375: 78-90) and ‘Two-ring hybrid externalfixation of distal tibial fractures: A review of 47 cases’ (RistiniemiJ., Flinkkilä T., Hyvonen P., Lakovaara M., Pakarinen H., Biancari F.,Jalovaara P., J. Trauma 2007; 62: 174-183), the contents of which isincluded in this as a reference. In addition, non-invasive rigidsupports are known, such as traditional plaster casts and similar.Supports permitting movement have been created, for example, by arrangedexternal hinge-type plates, with the aid of which an attempt has beenmade to imitate the movement of the damaged joint. An example of thesaid plate in cases like the ankle fracture described above is a kind ofpedal, on top of which the base of the foot is placed and which isadjusted to permit only such a tilting movement as would be natural fora healthy ankle.

Alternative methods are known for defining the natural movement of asynovial joint. In camera-based methods, the movement is recorded byusing, for example, a video camera and alignment marks, which areattached to the object to be moved. After recording the movement, thepreferably digital video material is analysed using special software andthe movement information obtained with the aid of the alignment marks iscaptured, in order to form the path of movement. This method is utilizedwidely, for example, in sports applications and in the film industry,for which the technology was originally developed. Because the methoddoes not require physical contact with the patient, the method is quiteuser-friendly from the patient's point of view. The accuracy of themethod varies from the accuracy required for making animations to theaccuracy required for quality control. However, in the final resort theaccuracy of the method depends on the resolution of the camera and onthe measurement volume used. Typically, sufficiently accurateinformation is obtained by means of the method for animation of themovement of an entire limb, but this technology does not provide ananswer to the movements of the bones that act as counter-surfaces in anindividual joint. A drawback of the method is that, in terms of the areaof the theme of the invention, the method cannot be used to determinereliably the movement of the bones under the actual tissues, but ratherthe movement of the tissue on top of the bones. In addition, thesemethods do not reveal the fine-dynamic flexing under the soft tissue,i.e. the dynamics between the bones. Because it has not been possible toaccurately define the precise anatomic movement, it has also not beenpossible, on the basis of these methods, to design anatomicallypersonalized external supports.

An alternative to camera-based methods are three-dimensional orradiographic methods, in which a three-dimensional model of the bones isformed on the basis of either computer tomography (CT) ormagnetic-resonance imaging (MRI). The methods are suitable for modellingthe shape of an individual bone. MRI is not, however, suitable forsituations in which steel screws or other attachment means in the areaof the joint already attached for old injuries or installed for the careof a new injury. In the said cases, CT imaging would be a possiblemethod, but it suffers from imaging interference caused by metals andfrom the great radiation stress caused to the patient.

In known applications, a damaged synovial joint and its part aremodelled on the basis of CT or MRI, when a virtual kinetic modelcorresponding to the damaged joint is obtained. This solution has beentypically used in early motion analysis studies of cases of injury,because the technology used has been readily available in a hospitalenvironment. For example, publication US2008312659 discloses a methodfor manufacturing a prosthesis, in which a patient-specific image, whichis used as an aid in the manufacture of the prosthesis, is formed fromdata obtained from MRI imaging. For its part, publication US2007118243discloses a method, in which a computer-based model, which is exploitedto manufacture implants, prostheses, and similar, is created from dataobtained on the patient's anatomy in CT imaging. Though CT and MRI-basedmethods are indeed suitable for the manufacture of patient-specificartificial joints and other implants, the use of the said methods doesnot achieve sufficient accuracy as would permit preserving and saving apatient's own joint after injury. Traditionally, it has been possible toachieve an accuracy of about 10 millimetres, whereas achieving a goodresult would require an accuracy of at least 1 . . . 3 millimetres,preferably at least 0.5 millimetres. Typically, significant swellingalso occurs in the area of a limb joint after injury, which reduces theaccuracy if the definition of movement or the support is based on skincontact.

In general, significantly unknown tolerances relate to the technologyused in the creation of bone models, which derive from the imagingquality and the grey-tome values available in sectioning. In addition,the joints, locations, and attitudes of three-dimensional models arefitted together visually in a 3D environment, which further reduces themethod's reliability and repeatability. Tolerance errors made in thecreation of bone models accumulate, when the attachment points aredesigned on the basis of the models. All in all, at least up until now,the CT and MRI-based three-dimensional method have not been applied,because sufficient accuracy cannot be achieved using the methods.

Thus, the problems of the prior art are related to the determining ofthe path of a damaged joint. Because each joint, tissue, and injury isdifferent, a statistical approximation and present modelling methodshave not been able to provide a solution for creating an anatomicallypersonalized support. More specifically, using present post-operativeexternal supports, i.e. supports external to the body, it has not beenpossible to place artificial or auxiliary joints sufficiently preciselyon the paths of movement of the joint, so that the mobilization of aninjured limb or similar will not succeed, due to which the cartilage ofthe joint will not receive nutrition reliably. As stated, in inmechanical design, as is known, reference geometries can be utilized,either by creating them in a three-dimensional 3D-CAD system, or bybringing a camera-based digital geometry to the design system, by usingvarious methods and various formats. Challenges generally arise in thecombination of a reliable design geometry, referencing digitalization,and a real application. Thus, the known joint supports have been rigid,which is not optimal from the point of view of the recovery of a joint.

The external support devices on the market, which a priori permitmovement to a limited extent around a single axis, are in point ofdeparture universal-type devices. It has therefore not been possible totake into account the size of the patient or soft-tissue damage, whichare important in terms of avoiding complications. In these cases, theattachment spikes must be placed in an area that has been very preciselydefined beforehand, while the location of the external axis cannot bedetermined other than visually with the aid of transillumination. Theprecision then remains unavoidably poor and the path small.

It is an object of the present invention to solve at least some of thedrawbacks of the prior art and to create an improved method for creatinga anatomically personalized and mobilizing external support forrehabilitating a synovial joint.

The object of the invention is achieved by means of a new type of methodfor creating an anatomically personalized and mobilizing externalsupport for supporting a synovial joint between two bone groups in sucha manner that it can be moved, in which method the kinetic dynamics ofthe joint are measured with the aid of a part of the external supportattached invasively to at least one of the said bone groups, on thebasis of which the external support is arranged between the bone groups.

According to one embodiment of the method according to the invention,the movement of the joint is measured using a co-ordinate measurementdevice and the measurement is performed from invasively attachedauxiliary frames, which form part of the external support and CAD modelsof which are arranged in a CAD environment. According to the embodiment,the measurement data of the co-ordinate measurement device and the CADmodels are combined in the CAD system, in order to model the path of thejoint and the external support.

According to one embodiment of the invention, a CAD model is arranged ofthe external auxiliary joint permitting the modelled path and this isplaced in the CAD environment between the auxiliary frames, on the sameaxis as that of the modelled path of movement, and, with the aid of theCAD models, at least one adapter component is arranged, which is fittedto combine the auxiliary frame and the auxiliary joint.

More specifically, the method according to the invention ischaracterized by what is stated in the characterizing portion of Claim1.

The object of the invention is achieved, on the other hand, by means ofa new type of external support to be fitted between the bone groups,which comprises at least one first external modular auxiliary frame,which is attached by invasive attachment means to the first bone group,at least one second external modular auxiliary frame, which is attachedto the second bone group, at least one external modular auxiliary joint,which is arranged between the first and second auxiliary frame, as wellas at least one personalized adapter component, which is arranged toconnect the auxiliary joint to the auxiliary frame.

More specifically, the external support according to the invention ischaracterized by what is stated in the characterizing portion of Claim15.

The object of the invention is achieved, on the other hand, by means ofa new type of use, in which part of an invasively attached externalsupport is used in defining the path of the joint to be supported.

Considerable advantages are achieved with the aid of the invention. Thisis because, by means of the method according to the invention, aparticularly accurate model of the movement of the damaged joint isachieved, thanks to which it is possible to design, manufacture, andinstall a precisely anatomically personalized and mobilizing externalsupport. Because a precise anatomical correspondence with the patient'sown joint is obtained from the mobilizing external support, themovements to be performed in post-operative rehabilitation will imitatethe natural path of movement of the joint. Thus, thanks to thismovement, the joint will receive nutrition promoting recovery and thewrong kind of movement will not cause additional damage to the joint. Interms of the success of later rehabilitation, both the preservation ofmuscle control and the prevention of contraction (shrinkage) of thetendons are very important. Complete locking of a joint for even a fewweeks will lead to detectable movement restrictions and also toimmobilization osteoporosis. However, with the aid of the inventionthese problems can be reduced. The accurate patient-specific path ofmovement of the joint also permits the use of soft fillers as a basisfor the regeneration of the structural parts of the joint. Thus, for theduration of recovery, the path of movement of an extensively damagedjoint is controlled using the external support device according to theinvention, in such a way that the movement takes place the whole time ina controlled manner, without a deforming force being directed to thesoft medium before it has regenerated sufficiently to form aload-bearing cartilage and bone under the cartilage. At the same time,the invention permits controlled movement exercises of the joint, forexample, as aftercare of ligament repairs.

Because, in the method according to the invention, it is possible to usedevices, which have been demonstrated to be reliable in otherconnections, the performance of each sub-area of the method has beenoptimized separately. This is because according to one embodiment thesupports to be attached to the bone group are Ilizahroz rings, which area particularly advantageous way of attaching external structures tolimbs. Correspondingly, according to one embodiment the measurement ofthe path of movement is performed using a co-ordinate measuring device,which has been shown in an engineering-shop environment to be suitablefor even demanding quality-control and even calibration applications.Thus, the method can be implemented using very different devicecombinations, the parts of which have been proved to be good in otherconnections. Thus, the method is not dependent on new technologiesuntried in practice.

According to one embodiment, the external support's auxiliary joint isadjustable, so that the movement permitted for a joint that has beenoperated on can be adjusted as recovery progresses. For example, thebone groups surrounding an injured joint can be locked to be immobilefor a couple of days after the operation, after which by adjusting theexternal support's auxiliary joint rehabilitation can be commenced instages according to the conditions for recovery, in the cases of boththe extent of movement and the degrees of freedom of the selectedmovements.

In addition, the invention permits the attachment spikes to be placedentirely freely, so that, for example, the damaged areas of the softtissues can be left free, thus reducing the risk of complications. Thisalso provides a possibility of choice to exploit the points achievingthe best skeleton grip in the bone attachments and both to acceleratethe operation as well as to reduce the amount of x-rays used in theoperating theatre.

In the following, some embodiments of the invention are examined indetail with reference to the accompanying drawings, in which

FIG. 1 presents a person's ankle, to which an external support, createdusing the method according to the invention, has been fitted,

FIG. 2 presents a seating used in measurements, and

FIG. 3 presents a CAD view from the design of a support according to oneembodiment of the invention.

The method according to the present invention can be applied to the careof numerous different joint injuries. The method according to theinvention is particularly suitable for, but not restricted to, the careof traumatic changes. Because joint injuries are caused to a very greatextent as a result of falling accidents, the method according to theinvention will be described hereinafter in the case of an example of anankle fracture, because it is an anatomically simple subject. Of course,the method according to the invention is also suitable for creating theexternal supports required in the case of other joint injuries. Atypical pilon fracture is associated with a falling accident that hastaken place due to negligence in work safety, or in connection with aphysical hobby, as a result of which the patient's ankle bone hasimpacted the cartilage surface of the tibia, which has resulted indamage to the joint between the ankle bone and the tibia. In the worstcase, the entire under surface of the tibia will have shattered.

As shown in FIG. 1, the damaged joint 40 is surrounded by at least twobone groups: a first bone group 10 and a second bone group 20. In thecase of the example of an embodiment described here, the first bonegroup 10 is the tibia and the second bone group 20 is the ankle bone andthe heel bone connected to it. In this connection, a group of bones,which consists of at least one bone, is regarded as being a bone group.In the case of the ankle-fracture example, the first bone group 10 thuscomprises only a single bone and the second bone group 20 comprises twobones. Immediately after the injury has occurred, the patient's ankle istypically fixed, i.e. supported rigidly using splints, a plaster cast,an external attachment device (external fixator), or some other rapidlyapplicable means, by which movement of the ankle is prevented. Often,swelling caused by the injury prevents the fracture pieces from beingimmediately returned to their places and the related internal attachmentusing screws, spikes, plates, or other implants. If the soft-tissuesituation permits, the ankle is operated on, in connection with whichthe pieces of cartilage are lifted off the tibia and returned to theiroriginal location. Traditionally, in the operation fixation is performedusing an Ilizahrov or other rigid support device, which is known.

According to the invention, in connection with the operation, auxiliaryframes 12, 22 are placed around the damaged joint 40, with the aid ofwhich an anatomically personalized and mobilizing external support canbe designed, manufactured, and installed outside the joint 40, whichwill permit the joint 40 to be able to be moved to the correct extent inthe correct directions, according to all the directions of movementrequired and measured in each joint. The auxiliary frames 12, 22 areattached invasively to the bone groups 10, 20 surrounding the joint 40,for example, using bone screws or various suitable cable arrangements.In this connection, the term invasive refers to a part penetratingtissue and the term external refers to a part outside the tissue. In theexample of FIG. 1, two invasive bone screws 21, which form the secondattachment means, are attached to the second bone group 20. The firstauxiliary frame 12, which is attached to the first bone group 10invasively with the aid of the first attachment means, which comprisethe bone screws and cables according to FIG. 1, is fitted to the firstbone group 10 surrounding the joint 40. The first auxiliary frame 12 ispreferably, for example, an Ilizahrov ring arrangement, which is easy tofit to the tibia according to the ankle embodiment. In the attachment ofthe auxiliary frame, the actual attachment point is, according to theinvention, of no particular importance: the attachment point, forexample for bone screws, is chosen on the conditions of the bestpossible contact and the most accommodating soft-tissue situation. Alsothe position and attitude of the auxiliary frame 12, 22 can be selectedquite freely, but, however, in such a way that the distance of theclosest point of the auxiliary frame from the coming external auxiliaryjoint is the smallest possible, either by visual estimate or bycalculation.

As can further be seen from FIG. 1, the second auxiliary frame 22 fittedto the second bone group 20 comprises, according to one embodiment, theheads of the bone screws 21. Alternatively, the second auxiliary frame22 could be, for example, a horseshoe-shaped ring resembling anIlizharov ring, which is attached to the second bone group by bonescrews 21. Generally, the auxiliary frame according to the invention canbe an arbitrary component, which can be fixed to the bone group and towhich an auxiliary joint 30 or adapter 32, which will be dealt with ingreater detail later, can be fitted externally.

Once the injured joint 40 has been repaired in an operation and theexternal auxiliary frames 12, 22 has been fitted to the bone groups 10,20 surrounding the joint 40, the movement of the joint 40 is modelledfor the design of a correct type of mobilizing external support.Immediately after the operation, the joint 40 is, however, fixedtemporarily, for example for a couple of days, by securing the auxiliaryframes 12, 22 to each other by a suitable intermediate part. Accordingto the invention, prior to this the movement is modelled preferablyusing a digitalization device, by means of which numerical and correctinformation is created. In this connection, the term digitalizationrefers to a device, by means of which movement information can becaptured from a physical object and data, such as a set of co-ordinates,for processing is created. According to one preferred embodiment, thedigitalization device is a co-ordinate device, for example theMicroScribe MX, by means of which in the best case accuracy of as muchas 0.05 millimetres can be obtained. Alternatively, it is possible touse, for example, a three-dimensional laser scanner, the use of whichhas, however, usability problems, because the application of themeasurement information created using the scanner in an external set ofco-ordinates is challenging. When using a co-ordinate measurementdevice, the measuring device and the subject of the measurement must beplaced mutually in the same set of co-ordinates. In practice, theco-ordinate measurement device and the first auxiliary frame 12 aresupported, in the ankle embodiment presented, for example, in anoperating theatre on furniture in such a way that the distance orattitude between them does not move during the measurement. In order tofacilitate the measurement, seatings 50, in which there is a recess 51for the measuring head of the co-ordinate measurement device (FIGS. 1and 2), are preferably fitted to the auxiliary frames 12, 22. Thanks tothe recess 51, the measuring head of the co-ordinate measurement devicecannot slide away from the measuring point, in order to improve thereliability and repeatability of the measurement. As FIG. 2 shows, theseating 50 is, according to one embodiment a stud, which is attached toa hole in the auxiliary frame 12, 22, and in which there is a recess 51or cavity with the same diameter as the measuring head, into which themeasuring head must be placed in the correct attitude. The left-handside of FIG. 2 shows the seating 50, which is equipped with a longrecess 51, so that the arm of the measuring head must be correctlyaligned when the measuring head touches the bottom of the recess 51. Theright-hand side of FIG. 2 show a seating 50 equipped with a shallowrecess 51. In both seatings 50, there is a hole on the opposite side tothe recess 51, which is arranged to receive the attachment element, bymeans of which the seating 50 is attached to the measurement object. Thefirst auxiliary frame 12, 22 is preferably designed in such a way thatthe measurement points of the seatings 50 placed in the holes aremutually on the same plane. Alternatively, a corresponding cavity orrecess 51 for the measuring head of the measurement device, promotingthe measurement, can be machined or otherwise precision-manufactured inthe auxiliary frame 12, 22.

In the measuring process, the intention is to obtain information of thekinetic dynamics of the joint, i.e. as to how the bone groups around thejoint move relative to each other, by means of the joint. Morespecifically, in the measurement, the movement between the first andsecond bone groups 10, 20 in respect to the joint 40 is measured withthe aid of the auxiliary frames 12, 22 attached to the bone groups 10,20 by attachment means 21. In the ankle embodiment described above, theco-ordinates of the measurement points of the auxiliary frame 12(Ilizahrov ring) attached to the first bone group 10, i.e. the tibia,are measured first. In the case of the example, at least three,preferably more, seatings 50 are attached to the first auxiliary frame12. Because the first auxiliary frame 12 is designed in such a way thatthe recesses 51 in the seatings 50 are mutually on the same plane, it iseasy, on the basis of the measurements to form a reference-geometryplane, which depicts the surface of the first auxiliary frame 12, towhich the auxiliary joint 30 is attached. Thus, there must be at leastthree measurement points, in order to form each spatial plane. Themeasurement points are preferably more than three, because in that casemeasurement errors can be evened out by approximating the resultscomputationally when forming the planes. In addition, it is good torepeat the number required, in order to eliminate measurement errors. Inthe case of the example above of an ankle joint, this is simplified tobecome a hinge joint.

Once the locations of the measurement points of the auxiliary frame 12of the first bone group 10 have been measured, the path of themeasurement point or points of the second auxiliary frame 22 relative tothe first auxiliary frame 12 is measured. The path can be measured, forexample, in such a way that the joint 40—in the case of the example theankle—is moved in a natural path relative to the joint 40, during whichtime at least three values are measured for the measurement point of thesecond auxiliary frame 22. Preferably as many attitudes as possible ofthe joint 40 on the path are measured repeatedly, in order to eliminatemeasurement errors and to determine the precise length of the path. Thesecond auxiliary frame 22 is also preferably equipped with a seating 50receiving the measuring head, especially preferably with a seating 50according to the example on the left-hand side of FIG. 2.

After, or during the measurements, the measurement data is transferredto a CAD system. According to one preferred embodiment of the invention,the measurement data is transferred from the co-ordinate measuringdevice directly to the CAD system, either through a common interface, orwith the aid of separate software. Alternatively, the information canalso be recorded in a file, from which the measurements points areloaded as points into the CAD program. Once the measurement informationis in the CAD system, the kinetic dynamics of the joint 40 are modelledon the basis of the information. In the modelling of the kineticdynamics 60, the movement of the joint 40 can be approximated andmodelled very accurately on the basis of the measurements obtained fromthe second auxiliary frame 22, by arranging the curve 64 to run throughthe measurement points (not imaginary), as shown in FIG. 3. On the basisof the curve 64, in the case of a hinge joint, the plane 63 of movementand the centre point 62, axis 61, and extreme points (ends of the curve)of the rotational motion can then be determined. In a joint comprisingseveral degrees of freedom, each rotation and sliding movementcombination is defined, as well as their mutual rhythm in each plane ina corresponding manner. On the basis of the measurement results obtainedfrom the first auxiliary frame 12, it is possible, on the other hand, tocreate a reference plane, relative to which the second bone group 20,i.e. the second auxiliary frame 22, moves (not shown). The referenceplane is created with the aid of at least three measured points, inwhich case the three points are set to connect the plane. Thecomputational creation of paths of motion, planes, and axis on the basisof measured points is, as such, known.

According to the invention, a CAD model is arranged from the auxiliaryframes 12, 22. In this connection, the term arranging, refers to thefact that the CAD model is created either by procuring it in aready-made form from a databank, in which the component has beenmodelled beforehand, or by forming a CAD model on the basis of anexisting component. In terms of the performance of the invention, it ispreferable for there to be a finished CAD model of the auxiliary frame,as well as of the components to be used, already prior to measuring, sothat the operating time will not be taken up in modelling. According toa particularly preferred embodiment, the components used, such as theauxiliary frames 12, 22, the attachment means 21, and the auxiliaryjoint 30 are standard components, of which there are ready-made CADmodels. The measurement points are also preferably modelled into the CADmodels of the auxiliary frames 12, 22, so that the adapting of themodels to the measured plane or measured axis will be easy. In addition,a CAD model is arranged of the auxiliary joint 30 (FIG. 1) used in theexternal support. The auxiliary joint 30 is preferably of ageneral-purpose model and a simple, readily available hinge-type pinjoint, the path permitted by which can be limited mechanically. Thehinge component can further be shaped according to modelling, in such away that it permits sliding of the rotational centre point and thealteration of the radius of the path. This is necessary, for example,when modelling the movements of the knee.

Once the kinetic dynamics 60 of the joint 40 have been created in theCAD system, the arranged CAD models of the auxiliary frames 12, 22 areadapted to the path in the CAD system. In the case of the ankle example,the surface of the first auxiliary frame 12 closest to the secondauxiliary frame 22 is placed, on the basis of the measurement results,in an attitude on the created plane (not shown), in which themeasurement points coincide with each other. Correspondingly, the CADmodel of the auxiliary joint 30 is placed on the path, in such a waythat the axis of the auxiliary joint 30 and the axis 61 of the pathcoincide, so that the CAD model of the auxiliary joint 30 simulates thejoint permitted by the path 64 brought into the CAD system. Preferably,kinetic centre point of the model of the auxiliary joint 30 coincideswith the centre point 62 of the modelled motion. Once the length of thepath is known on the basis of the model of the path, the extent ofmotion of the real auxiliary joint 30 is adjusted preferably tocorrespond to the measured natural extent of motion of the joint 40.Correspondingly, the CAD model of the second auxiliary frame 22 isaligned in place in the CAD system on the basis of the model of thepath. The modelled measurement point or points are also preferablymodelled in the CAD model of the second auxiliary frame 22.

Once the auxiliary frames 12, 22 and the auxiliary joint 30 have beenadapted in the CAD system to the created path model, the necessaryadapter components 31, 32 for connecting the auxiliary joint 30 to theauxiliary frames 12, 22 (FIG. 1) are modelled in the system. In somecases, the auxiliary joint 30 can be adapted to be connected directly tothe auxiliary frame 12, 22, in which case only a single adaptercomponent 31, 32 will be required. According to one embodiment, as shownin FIG. 1, an adapter component 31, 32 is designed between both thefirst and the second auxiliary frame 12, 22 and the joint 30. It isparticularly advantageous to design the adapter components 31, 32directly in the CAD system to connect the joint 30 and the auxiliaryframes 12, 22, in which case drawings for manufacture can be obtainedespecially easily from the CAD models of the components 31, 32.According to one embodiment of the invention, the adapter components 31,32 are manufactured using a 3D printer, or by some other instantmanufacturing method, by means of which it is possible to manufacture,for example, polymer parts directly with the aid of CAD models.Alternatively, it is possible to use some other CAD-CAM system, by meansof which a component of sufficient strength can be created, and whichcan be manufactured rapidly. For example, the component can be machinedfrom aluminium in a machining centre, or manufactured instantly usingsome other technologies. The manufacture of pieces directly on the basisof CAD models is, as such, known.

Once the adapter components 31, 32 have been manufactured, they arefitted to the corresponding auxiliary frames 12, 22. The auxiliary joint30 is fitted between the adapter components 31, 32, in which case ananatomically personalized and mobilizing external support is createdoutside the joint 40 between the first and second bone groups 10, 20. Asstated, the auxiliary joint 30 is preferably adjustable, in such a waythat the angle between it and the movement of the actual joint 40 can beadjusted. Immediately after the operation, the auxiliary joint 30 isadjusted, preferably in such a way that the movement between the firstand second bone groups 10, 20 does not permit the bone groups to fix.During the period of post-operative rehabilitation, the path and angleof the movement permitted by the auxiliary joint 30 is adjusted on thebasis of the CAD model of the path to be anatomically correct and theextent of the paths of motion can be adjusted as required as careprogresses.

According to one embodiment, the method according to the invention isused in connection with a joint operation, in which operation a softmass suitable for the purpose is utilized, which is arranged todifferentiate in different support tissues when the joint experiencesmanipulation on the standard path. In the embodiment, the joint isoperated on using the technique described, in which the destroyed jointsurfaces are removed and is replaced by a mass like that described,which can differentiate into different types of tissue. In theembodiment, an external support according to the invention, which isparticularly advantageous in connection with precisely the said mass, isarranged for the joint that has been operated on.

The embodiment described above, in which there is an anatomicallypersonalized external support, designed, manufactured, and installedaccording to the invention, for repairing an ankle injury, is only onemanifestation of the invention. The method according to the inventioncan also be applied to the rehabilitation of other joints, for instancethe knee, elbow joint, or, for example, the wrist. Thus, the embodimentdepicted above is not intended as a limiting specification, but ratheras an exemplary description. One skilled in the art will naturally adaptthe method, device, and use according to the invention to other thanhuman patients. The present invention can also be implemented in asequence differing from that described here. For example, the joint canbe operated on and supported in the operation rigidly in a suitablemanner, e.g., using a Ilizahrov ring. Once the joint permits movement,the rigid support can be removed and the invasive structures, i.e.auxiliary frames, can be utilized in measuring the movement of thejoint, after which the necessary auxiliary joints and adapter componentscan be arranged according to the invention.

TABLE 1 List of reference numbers. Number Part 10 first bone group 12first auxiliary frame 20 second bone group 21 attachment means 22 secondauxiliary frame 30 auxiliary joint 31 first adapter component 32 secondadapter component 40 joint 50 seating 51 recess 60 CAD model of joint'skinetic dynamics 61 axis of rotation 62 centre point of rotation 63plane of motion 64 path (measured points)

1. An anatomically personalized and mobilizing external support betweena first and a second bone group, which support comprises: at least onefirst external modular auxiliary frame, which is configured to beattached to the first bone group using invasive attachment means, atleast one second external modular auxiliary frame, which is configuredto be attached to the second bone group, at least one external modularauxiliary joint, which is fitted between the first and the secondauxiliary frame, which at least one external modular auxiliary joint isconfigured to permit: rotation about a rotational centre point on a pathhaving a radius as well as sliding of the rotational centre point andthe alteration of the radius of the path, at least one personalizedadapter component, which is arranged to connect the auxiliary joint tothe auxiliary frame and which at least one external modular auxiliaryjoint is made by additive manufacturing or machining.
 2. Theanatomically personalized and mobilizing external support according toclaim 1, wherein in the auxiliary frames there are measurement points,which are arranged to receive the measuring head of a coordinatemeasuring device.
 3. The anatomically personalized and mobilizingexternal support according to claim 1, wherein the at least one externalmodular auxiliary joint is adjustable in such a way that the anglebetween the at least one external modular auxiliary joint and themovement of a patient's joint between the first and second bone groupcan be adjusted.
 4. The anatomically personalized and mobilizingexternal support according to claim 1, wherein the external supportcomprises bone screws or cables or both as invasive attachment means forfixing the at least one first external modular auxiliary frame and theat least one second external modular auxiliary frame to the first andsecond bone group, respectively.